1. Field of the Invention
The present invention relates to an image projection apparatus that uses a lamp to project an image onto a projected surface, such as a screen.
2. Description of the Related Art
A light source of an image projection apparatus, such as a liquid crystal projector, often employs a lamp, such as an ultra high-pressure mercury lamp.
The image projection apparatus that cools the lamp by utilizing a cooling fan in order to maintain the temperature of a light emitting tube in the lamp in a proper range. In general, the lamp includes a reflector, and a light emitting tube arranged inside of the reflector, and each of the inside of the reflector (light emitting tube) and the outer surface of the reflector (outer circumference of the lamp) is cooled by the air.
Usually, the lamp is arranged near an exhaust port formed in the housing of the image projection apparatus, and the air that has cooled the lamp and becomes at a high temperature is immediately exhausted to the outside of the housing by an exhaust fan provided between the lamp and the exhaust port.
However, when the high-temperature air that has cooled the lamp is exhausted as it is from the exhaust port, a user near the exhaust port receives hot winds and feels uncomfortable. Thus, it is necessary to make the temperature of the air as low as possible which has cooled the lamp.
Japanese Patent Laid-Open No. 9-83914 discloses an image projection apparatus that uses the air from the fan to cool the lamp, draws the open air into the housing, blends the open air with the air that has cooled the lamp, and exhausts the blended air from the exhaust port. In addition, Japanese Patent Laid-Open No. 2005-43602 discloses an image projection apparatus that includes two air trunks, i.e., one air trunk being configured to cool the inside of the reflector of the lamp, and the other air trunk being configured to cool the outside of the reflector. In this image projection apparatus, the air that has passed two air trunks cools the lamp is then led to an inlet port surface of an exhaust fan by an exhaust duct, blended with the air that has cooled another member on the inlet port surface of the exhaust fan, and exhausted to the outside of the exhaust fan.
However, the image projection apparatuses disclosed in Japanese Patent Laid-Open Nos. 9-83914 and 2005-43602 are configured so that just before the inlet port surface of the exhaust fan, a current of the open air or the air that has cooled another component is joined with a current of the air that has cooled the lamp. Since this configuration insufficiently blends the high-temperature air that has cooled the lamp with the open air or the air that has cooled the other component, the air that has cooled the lamp and remains at a high temperature leaves in part of the exhaust air to the outside of the housing.